A robot can be quantified as humanoid from the moment it possesses certain attributes of human appearance and functionalities: a head, a trunk, two arms, two hands, two legs or two feet. Humanoid robots are capable of walking, making gestures, with the limbs or with the head. The complexity of the gestures that they are capable of performing is constantly increasing. Despite these advances, the humanoid robots remain susceptible to falling. These falls can occur during robot debugging tests, but also in a subsequent phase of use of the robot, because of the inevitable obstacles or external interventions. To allow for a consumer application, the humanoid robots need to be able to withstand such falls repeatedly.
A particular difficulty stems from the relatively high position of the center of gravity of a humanoid robot. For example when a robot with a size of 70 cm falls, the deceleration undergone by the components of the head striking the ground can reach values of the order of 70 G. These undesirable but inevitable falls are likely in the current robots to damage the fragile components, such as the electronics or the sensors and actuators.
In a known approach, attempts have been made to circumvent this difficulty by lowering the center of gravity. A robot is for example known in which the lower part in skirt form houses the heaviest equipment items. This approach does however have the drawback of limiting the movements and functionalities of the upper part of the robot, in particular of the arms and of the head. To improve the resistance of the robot to falls, protection mechanisms have also been considered that are configured to be triggered when a fall of the robot is detected. This approach also presents limitations, in particular the untimely triggering of the protection mechanism during movements of the robot.
It therefore remains desirable to have solutions available to improve the mechanical strength of the humanoid robots and allow them to withstand repeated shocks against the latter. Obviously, such a solution needs to be able to fit into the functional and structural environment of the robot.